The invention relates to an energy-optimized acceleration control for a motor vehicle having an internal-combustion engine and/or an electric drive motor, a transmission unit and/or an accelerator element to be operated by the driver for accelerating the motor vehicle.
In order to be able to accelerate in an energy-optimized manner, in the case of passenger cars at low rotational speeds, the driver has to depress the accelerator pedal by approximately ¾ of the total accelerator pedal travel. Different approaches exist for making it easier for the driver to find the correct accelerator pedal position for an energy-optimized acceleration, which generally allows for driving in the energy-efficient power range.
Thus, a system is known that has an active accelerator pedal. In this case, the energy-optimized acceleration is continuously haptically indicated to the driver by way of the active accelerator pedal by a controlled pressure point in the course of the restoring force. However, an active accelerator pedal requires high construction and control expenditures, which leads to high development and manufacturing costs.
Simpler and more cost-effective systems generate only a fixed pressure point in the course of the restoring force. Thus, DE 31 22 268 A1 discloses a fuel-saving device in the form of a spring element to be retrofitted under the accelerator pedal. As a result, (when the spring element is reached) a pressure point is generated in the course of the restoring force, so that the driver is prevented from accidentally depressing the accelerator still further and thereby causing an increased fuel consumption.
From the type-forming EP 1 297 987 A1, a timing gear control is known for a vehicle having a manual transmission, in which case a fixed pressure point or inflection point is also provided in the course of the restoring forces of the accelerator pedal. The restoring force rises in an intensified manner when this pressure point or inflection point is reached. In the case of a position of the accelerator pedal between the inoperative position and the inflection point, only a first operating mode of the valve gear control can occur, a second operating mode occurring behind the inflection point. The first operating mode may be an engine operation with a stoichiometric air-fuel ratio, in which case the throttle valve is at least partially closed. The partial closing of the throttle valve causes a limitation of the engine power, whereby a particularly economical operation of the motor vehicle is ensured. Such a method may have the result that, because of the power reduction in the first operating mode, the driver may feel that the decision is not left up to him, because this first economical operating mode will already be present when the driver does not depress the accelerator pedal or depresses it only slightly.
It is now an object of the invention to provide a cost-effective and easily implementable energy-optimized acceleration control for a motor vehicle, based on which the driver will only be driving in an energy-optimized or energy-efficient mode if he in fact desires to do so.
This and other objects are achieved by an energy-optimized acceleration control method and apparatus according to the invention for a motor vehicle having an internal-combustion engine and/or an electric drive motor, a transmission unit and an accelerator element to be operated by the driver for accelerating the motor vehicle (in which case a restoring force acts upon the accelerator element when the accelerator element is operated). The driver is assisted with respect to a more energy-efficient acceleration operation by a simple constructive further development of the accelerator element. For this purpose, a fixed inflection point (similar to the kick-down inflection point in the case of vehicles with automatic transmissions) is provided in the course of the restoring force when the accelerator element is operated. This fixed inflection point can be felt by the driver as a pressure point with an increased resistance when the accelerator element is operated correspondingly. The inflection point can, for example, be noticed by the fact that the restoring force increases erratically or by the fact that at least the gradient of the restoring forces clearly changes at this inflection point. The inflection point (or the increased resistance existing at the inflection point) can be generated, for example, by way of an appropriately designed auxiliary spring. The acceleration control is suitable for vehicles with an internal-combustion engine as well as for vehicles having a hybrid drive unit consisting of an internal-combustion engine and an electric drive unit, or vehicles having only an electric drive unit (so-called electric vehicles).
The invention is now characterized in that, when the accelerator element is operated until the inflection point has been reached, the acceleration control is changed such that an energy-optimized or energy-efficient accelerating of the motor vehicle becomes possible. For this purpose, a change into an energy-optimized acceleration mode takes place when the inflection point is reached. Since the driver's desire for an “energy-optimized acceleration can be clearly detected by way of the inflection point, it becomes possible to optimally condition the vehicle starting from the reaching of the inflection point with respect to an energy-optimized acceleration.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.